Machine and method for forming articles

ABSTRACT

A machine and method of forming an article generally comprising extruding a molten bead of thermoplastic material along x, y and z axes in forming an article consisting of a strata of such material, and passing a roller over each applied portion of such molten bead to compress such bead portion, enhancing the fusion of engaging plies of such extruded material.

BACKGROUND OF THE INVENTION

In the prior art, there has been developed a process generally referredto as an additive manufacturing process which generally consists offorming and extruding a bead of molten thermoplastic material, applyingsuch bead of molten material in a strata of layers to form a facsimileof an article and then machining such facsimile to provide an endproduct. Typically, such thermoplastic material is infused with a typeof reinforcing fiber to enhance its strength. As a general practice, themolten bead, while still hot and pliable, is tamped down using anoscillating plate to create a flattened layer of material of a specificdesired thickness. This process is repeated so that each layer isdeposited upon an existing layer to build up a structure. When executedproperly, the new material being deposited is of a temperaturesufficient enough to allow it to melt and fuse with material previouslydeposited, thus producing a solid part. The tamping plate is generallyconfigured as a flat plate with a center through-hole, situatedconcentric with the centerline of the extrusion nozzle, thus providingfor effective tamping of the extruded material, regardless of thedirection in which the head is moving. This tamping plate not only tampsand flattens the thermoplastic bead but also helps fuse it with thepreviously laid layer of material.

In the practice of the aforementioned process, several disadvantageshave been encountered; most notably, air pockets, which are trappedbetween layers of thermoplastic material during the extrusion/depositionprocess, are simply tamped into the structure. In addition to creatingproblems during any temperature cycling that might occur after the parthas cooled and hardened, such entrained air pockets invariably result ininternal voids as well as surface imperfections in the final machinedarticle. A further disadvantage of using a tamping plate is theinsufficient integration of reinforcing fibers between layers. When twosmooth beads of this material are forced together, the plastic componentof the bead tends to fuse with the plastic component of the mating bead,with little or no reinforcing fibers crossing the area where the layersmeet. Consequently, the joints between layers where there is noreinforcing material seriously affect the structural integrity of theoverall article. Additionally, the mechanism employed to quicklyoscillate the tamping plate is by necessity, quite complex, expensiveand difficult to maintain.

In view of the forgoing, it is the principal object of the presentinvention to provide an improved method of producing articles throughthe use of an additive manufacturing process. Another object of theinvention is to provide such a machine and method functional to providemore effective fusion of engaging plies of molten material. A stillfurther objective of the invention is to provide such improved machineand method without the requirement of complex and expensive devices.

BRIEF DESCRIPTION OF THE INVENTION

The principal object of the present invention is achieved by means of aprogrammable CNC machine operable in forming an article supported on awork surface disposed in an x-y plane, either fixed or displaceablealong an x-axis; an extruder disposed along an axis fixed ordisplaceable along an x-axis, displaceable along y and z axes, rotatableabout its axis and pivotal about an x-axis; means for supplying a beadof molten plastic material through such extruder; means cooperable witheither such work surface or a previously applied ply of such materialfor guiding and compressing a portion of such bead emanating from suchextruder in forming an article consisting of stratified layers of suchextruded material; a set of servomotors operable in displacing suchcomponents linearly, rotationally and/or pivotally and a suitablyprogrammed computer for operating such motors. Such means for guidingand compressing a portion of such bead of molten material emanating fromsuch extruder comprises a roller provided with an axis of rotationdisposed along a line of intersecting of a first plane disposedperpendicular to the axis of the material emitting passageway of suchextruder and a second plane disposed parallel to such passageway axis.Preferably, such bead of molten material is provided with reinforcingfibers interspersed therein which function to enhance the fusion ofadjoining plies of such material, guided and compressed by such roller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a CNC machine operable pursuant to anadditive manufacturing process in forming articles, incorporating thepresent invention;

FIG. 2 is an enlarged perspective view of the carriage and applicatorassembly of the machine shown in FIG. 1;

FIG. 3 is an enlarged perspective view of the lower segment of theapplicator assembly shown in FIG. 2;

FIG. 4a is an enlarged cross-sectional view of the material applicatorhead mounted on the lower end of the applicator assembly, illustratingthe nozzle of a conduit for supplying a molten bead of thermoplasticmaterial fully inserted into a passageway therethrough;

FIG. 4b is a view similar to the view of FIG. 4a , illustrating thenozzle thereof fully inserted into the passageway thereof;

FIG. 5 is a view similar to the view shown in FIG. 4a , illustrating abead of molten material being extruded by the applicator bead shown inFIG. 4a onto a work surface, and a roller thereof engaging andcompressing a portion of such bead against such work surface, forming aply of an article being formed;

FIG. 6a is an enlarged perspective view of the lower end of the assemblyshown in FIG. 2, provided with a roller formed with transversely spacedgrooves; and

FIG. 6b is a view similar to the view shown in FIG. 6a but with a rollerformed with a transversely curved configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Referring to FIG. 1 of the drawings, there is illustrated a programmablecomputer numeric control (CNC) machine embodying the present inventionwhich includes a bed 20 provided with a pair of transversely spaced sidewalls 21 and 22, a gantry 23 supported on side walls 21 and 22, carriage24 mounted on gantry 23, a carrier 25 mounted on carriage 24 and anapplicator assembly 26 mounted on carrier 25. Supported on bed 20between side walls 21 and 22 is a worktable 27 provided with a supportsurface disposed in an x-y plane, which may be fixed or displaceablealong an x-axis. In the displaceable version, the worktable isdisplaceable along a set of rails mounted on the bed by means ofservomotors mounted on the bed and operatively connected to theworktable. Gantry 23 is disposed along a y-axis, supported at the endsthereof on end walls 21 and 22, either fixedly or displaceably along anx-axis on a set of guide rails 28 and 29 provided on the uppers ends ofside walls 21 and 23. In the displaceable version, the gantry isdisplaceable by a set of servomotors mounted on the gantry andoperatively connected to tracks provided on the side walls of the bed.Carriage 24 is supported on gantry 23 and is provided with a supportmember 30 mounted on and displaceable along a set of guide rails 31, 32and 33 provided on the gantry. It is displaceable along a y-axis on suchrails by a servomotor mounted on the gantry and operatively connected tosupport member 30. Carrier 25 is mounted on a set of spaced, verticallydisposed guide rails 34 and 35 supported on the carriage fordisplacement of the carrier relative to the carriage along a z-axis. Itis displaceable along such axis by a servomotor mounted on the carriageand operatively connected to the carrier.

As best shown in FIG. 2, carrier 25 is provided with a base platform 36,a gear box 37 fixedly mounted in the upper side thereof and a mountingplatform 38 rotatably mounted on the underside thereof, provided withopenings therethrough disposed along the z-axis of the carrier. Suchgear box is provided with a gear arrangement provided with an openingtherethrough disposed coaxially with the aligned openings in gear box 37and platforms 36 and 38, operatively connected to platform 38 forrotation about such x-axis, and rotatable about such axis by means of aservomotor 39 mounted on base platform 36 and operatively connected tosuch gear arrangement.

Applicator assembly 26 includes an upper segment 41 and a lower segment42. Segment 41 includes a transverse portion 41 a secured to theunderside of mounting platform 38 for rotational movement about thez-axis, provided with an opening therethrough along such z-axis, and adepending portion 41 disposed laterally relative to such axis. Segment42 consisting of a housing disposed on an inner side of dependingsegment portion 41 b, is mounted on a shaft journalled in a lower end ofportion 41 b, intersecting and disposed perpendicular to the z-axis ofcarrier 25, and further is provided with a laterally projectingapplication head 43 at a free end thereof. Mounted on a bracket 44provided on an outer side of segment portion 41 b is a servomotor 45operatively connected to the shaft journalled in portion 41 b forpivotally displacing segment 42 in y-z plane.

Referring to FIGS. 4a and 4b , applicator head 43 includes a housing 46mounted on and projecting laterally from the lower end of segment 42,and a bracket 47. Housing 46 is provided with a cylindrical opening 48therethrough provided with an enlarged portion, a roller bearing 49mounted in such enlarged portion of such opening and a cylindricalsleeve 50 disposed in such enlarged portion, mounted on the inner raceof such bearing, having an inner diameter corresponding to opening 48and including a portion extending beyond housing 46. Housing opening 48and sleeve 50 are configured to receive therein a nozzle 51 of aflexible conduit 52 for conveying and extruding a molten bead 53 of athermoplastic material through such nozzle provided with an output die54 as shown in FIG. 5.

Bracket 47 includes an annular base portion 55 coaxially mounted on thelower, exposed end of sleeve 50 and rotatable with sleeve 50 about theaxis thereof, an annular plate portion 56 coaxially mounted on annularbase portion 55 and spaced axially relative to bearing 49, and asprocket 56 a mounted on base portion 55, coaxially on exposed portion55. Bracket 47 further includes a pair of spaced depending brackets 57,57 supporting a shaft 58 on which there is mounted a rotatable roller59. The axis of rotation of shaft 58 is disposed along the line ofintersection of a first plane disposed perpendicular to the axis ofpassageway 48 and a second plane disposed parallel to such axis.

As best shown in FIG. 3, bracket 47 is rotatably displaceable about theaxis thereof by a servomotor 60 supported on an L-shaped bracket 61mounted on a lower rear side of lower applicator segment 42, having anoutput shaft 62 projecting through an opening 63 in bracket 61, providedwith a sprocket 64 drivingly connected to sprocket 56 by means of a belt65.

Conduit 52 consists of an elongated, flexible material for conducting amolten bead of a thermoplastic material under pressure from a sourcedisposed on carrier 25 or another source, to applicator head 43. Anintermediate portion of such conduit is routed through the openingsthrough gear box 37, support platform 36 and mounting platform 38, alongthe z-axis of carrier 25. Such material is heated sufficiently to form amolten bead thereof, readily guide such bead through conduit 52 andextrude it through applicator head 43 in forming a strata of pliesfusing together in forming an article. Such material supplied throughsuch conduit and extruded to form an article may be provided with fiberswhich facilitate and enhance the fusion of extruded, engaging plies.

In the use of the machine as described in forming an article pursuant tothe additive manufacturing method, with the machine suitably programmedand activated, a bead of molten material would be extruded along adefined path either on support surface 27 of the machine or previouslyextruder plies of such material, ahead of the path of roller 59, andcaused to be engaged and compressed by such roller either against suchsupport surface of a previously applied heated ply of material, fusingsuch plies together to form an object consisting of a strata of materialplies fused together forming either an end product or an oversized, nearduplicate thereof.

In the course of forming such article, the control system of themachine, in executing the inputted program, would operate the severalservomotors as described to displace the support surface or gantry alongthe x-axis, displace the carriage along the y-axis, displace the carrieralong a z-axis, pivot lower applicator segment 42 about an axis disposedin an x-y plane and rotate bracket 47 about a z-axis thereof, pursuantto the inputted program, to provide the described end product or anoversized, near duplicate thereof.

The bead engaging portion of roller 59 may be cylindrical as shown inFIG. 5, serrated as shown in FIG. 6a or curved along the length thereofas shown in FIG. 6b . In circumstances where reinforcing fibers areprovided in the molding material applied, it is preferred to utilize aroller with an irregular surface as shown in FIG. 6a which is effectivein causing outlying portions of such fibers to engage and penetrateheated adjacent plies, enhancing the fusion of such plies.

In the practice of the invention as described, an article may be formedsimply by forming a strata of plies defining the intended finalconfiguration of the article; forming a strata of plies defining aninterim configuration minimally exceeding the intended finalconfiguration and then machining such interim configuration to providethe final configuration thereof; providing a permanent substructurepreferably of a metal, having a configuration smaller than the intendedfinal configuration of the article, and forming a strata of plies onsuch substructure providing the intended final configuration of thearticle; providing a permanent substructure preferably of a metal,having a configuration smaller than the intended final configuration ofthe article, forming a strata of plies on such substructure in formingan interim configuration slightly greater than the intended finalconfiguration and then machining such interim configuration to providethe intended final configuration; providing a mold having aconfiguration smaller than the intended final configuration of thearticle, forming a strata of plies on such mold slightly greater thanthe intended final configuration of the article, machining such interimconfiguration to provide the final configuration of the article and thenremoving such mold; and providing a mold having a configuration smallerthan the intended final configuration of the article, forming a strataof plies on such mold slightly greater than the intended finalconfiguration of the article, machining such interim configuration toprovide the final configuration of the article and then removing suchmold.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentinvention, which come within the province of those persons havingordinary skill in the art to which the aforementioned inventionpertains. However, it is intended that all such variations not departingfrom the spirit of the invention be considered as within the scopethereof as limited solely by the appended claims.

1-40. (canceled)
 41. A computer numerical control (CNC) machine,comprising: a nozzle for extruding a bead of material; an applicatorhead including a passageway therethrough configured to receive thenozzle, a bearing having an inner race coupled to a sleeve, and a firstbracket coupled to the sleeve; and a roller attached to the firstbracket.
 42. The CNC machine of claim 41, wherein the roller dependsfrom the first bracket via a pair of second brackets.
 43. The CNCmachine of claim 41, wherein the roller includes a set of annulargrooves disposed concentrically with an axis of rotation of the roller.44. The CNC machine of claim 41, wherein the roller is curved along alength thereof.
 45. The CNC machine of claim 41, wherein the rollerincludes a serrated outer surface.
 46. The CNC machine of claim 41,further including one or more servomotors configured to displace thenozzle such that the bead of material is extruded along a defined pathahead of a path of the roller.
 47. The CNC machine of claim 41, whereinthe roller is rotatable about an axis orthogonal to an axis of thenozzle.
 48. A computer numerical control (CNC) machine, comprising: anozzle for extruding material; an applicator head including a housing, asleeve rotatably disposed within the housing, and a bracket mounted onthe sleeve, wherein the applicator head includes an opening that passesthrough the housing, the sleeve, and the bracket, and wherein the nozzleis positioned within the opening; and a rotatable roller depending fromthe bracket of the applicator head.
 49. The CNC machine of claim 48,wherein the roller has a transversely curved configuration.
 50. The CNCmachine of claim 48, wherein the roller is rotatable about an axisperpendicular to a longitudinal axis of the opening.
 51. The CNC machineof claim 48, further including a carrier movable along a plurality ofaxes, wherein the applicator head is coupled to the carrier.
 52. The CNCmachine of claim 48, wherein the bracket is rotatable about alongitudinal axis of the opening.
 53. The CNC machine of claim 48,wherein the opening is cylindrical.
 54. The CNC machine of claim 48,wherein the material is supplied to the nozzle through a flexibleconduit.
 55. A computer numerical control (CNC) machine, comprising: acarrier displaceable along a plurality of axes; a nozzle for depositinga material; a flexible conduit connecting a source of the material withthe nozzle; an applicator head connected to the carrier, the applicatorhead including a passageway therethrough for receiving the nozzle; abracket mounted on an underside of the applicator head and rotatableabout a first axis; and a roller depending from the bracket androtatable about a second axis, wherein the second axis is orthogonal tothe first axis.
 56. The CNC machine of claim 55, wherein the carrierincludes a gear box, a support platform, and a mounting platform, andwherein the conduit extends through each of the gear box, the supportplatform, and the mounting platform.
 57. The CNC machine of claim 55,wherein the nozzle is configured to extrude the material ahead of a pathof the roller.
 58. The CNC machine of claim 57, wherein the roller isconfigured to engage and compress the material deposited along the pathof the roller.
 59. The CNC machine of claim 55, wherein the rollerincludes a varying cross-sectional diameter.
 60. The CNC machine ofclaim 55, wherein the roller includes a plurality of annular grooves.